Magnesium hydroxide is known to be a commercially useful non-halogen based flame retardant additive for polyolefins such as polypropylene. However, the shortcomings associated with the use of magnesium hydroxide are well established. For example, high additive loadings are required to reach desirable flame retardancy ratings such as UL-94 V-0 or even V-1 or V-2. Typically, magnesium hydroxide loadings in excess of 50% by weight are required, and to get the desirable UL-94 ratings of V-0 with sections of polyolefins as thin as 1/16", loadings as high as 65% are barely sufficient to provide requisite levels of flame retardancy. At such high loadings, the polyolefin composition tends to be stiff and brittle, especially if the polyolefin is polypropylene. At slightly lower levels of magnesium hydroxide, such as 60%, with thin sheets, UL 94 ratings of V-2 may not be attainable. As stated above, at higher additive loadings or with thicker sections, V-2, V-1, and V-0 ratings can be reached but the resulting magnesium hydroxide containing polyolefin compositions are too stiff and brittle.
The high density of magnesium hydroxide relative to polypropylene also leads to a heavy filled plastic, which is a disadvantage for many applications such as vehicle parts. Furthermore, the high loading of mineral filler also reduces the speed of processing and increases the wear on dies and molds.